The article explores for the first time the characteristics of the style of chamber instrumental works by Margarita Ivanovna Kuss (1921–2009), whose compositions were performed in various concert venues both in Russia and abroad. Leading domestic composers and musicians - G. Sviridov, D. Shostakovich, B. Tchaikovsky, N. Peiko, A. Eshpai, R. Ledenev, E. Svetlanov, V. Fedoseev, M. Miroshnikova - highly valued the creative legacy of M. Kuss. However, to date, there is only one work dedicated to her oeuvre, authored by Yu.B. Abdokov. This article presents an overview of the composer's chamber instrumental opuses - the First and Second Sonatas for violin and piano, as well as a detailed analysis of the Third Sonata for violin and piano. The research is based on a theoretical-analytical approach that allows for a systematic study of musical works, focusing on characteristic features of the composer's techniques, including the analysis of melodic, harmonic, and instrumental means of expression. The article represents the first large-scale study of the characteristics of M.I. Kuss's chamber instrumental compositions. For the first time, the memories and reflections of well-known contemporaries of Margarita Ivanovna are introduced into scientific circulation, offering a new perspective on the specifics of her creative work. The conducted analysis of chamber instrumental compositions reveals the unique features of the author's compositional style. The study makes a significant contribution to the understanding of domestic musical art in the second half of the 20th - early 21st centuries, expanding the knowledge of the development of chamber music during this period. The results obtained can be used in further research on the work of M.I. Kuss and on domestic musical heritage as a whole, as well as in the possibility of utilizing the article's materials within university courses such as "History of Russian Music" and "Analysis of Musical Works."